Need ideas on how to make my art look t-shirt worthy

I am normally a self-sufficient artist who refuses to ask for help but I am completely stumped. I have created a character called Billy the killer, all my pieces of work thus far containing him are here http://dsaintd.deviantart.com/gallery/45089916

Billy has been made half famous because I'm using a completely new style of art for me to create these pictures. I photoshop my pen drawings of him onto real pictures to give him the look of being a real life drawn character...but I am absolutely at a loss as to how to make something using him look well on a t-shirt.

....Except if the character looks really awesome got great colors and awesome details.. What chuck said. It can win, but you need a good background for it.. Judging from that kind of character a great concept it "Killing someone but in a funny way" because he looks funny but still that mask gives me creeps. Another opinion is create a dark colored background and then put him in it, he will stand out since he is just white.

I agree that the character needs a story, and one that the customers can easily pick up and understand. You should ask yourself: Would someone who doesn't know Billy's story get the humor behind the t-shirt design? A strong concept is the first step to a great design. Also, although I know your style is pen drawings over real images, for a t-shirt it would read better as one or the other (although I could see this type of work translating well to a vector). Hope that helps!

I agree that the character needs a story, and one that the customers can easily pick up and understand. You should ask yourself: Would someone who doesn't know Billy's story get the humor behind the t-shirt design? A strong concept is the first step to a great design.

Yeah I see this now, only myself and people who have been following his story on one of my sites would get the humour and idea behind it. I have plenty of other good concepts/ideas so I will focus more on them for t-shirts and leave this character style work for the art.